feat: Add CoAP protocol support to serial modem

zavdimka · zavdimka · commit 84d59a6f09ed · 2026-02-17T14:26:20.000-03:00
- Implement sm_at_coap.c with CoAP protocol handling
  - Support for multiple CoAP contexts (up to 3 simultaneous connections)
  - CoAP socket management and message handling
  - TLS/DTLS credential support
  - CoAP payload buffering (512 bytes)

- Update CMakeLists.txt to include CoAP source file
  - Add conditional compilation with CONFIG_COAP flag
  - Integrate sm_at_coap.c into the build system

- Add overlay-coap.conf

This enables CoAP protocol communication capabilities in the serial modem application.

Signed-off-by: Dmitrii Zavrazhnov &lt;zavdimka@gmail.com&gt;
diff --git a/app/CMakeLists.txt b/app/CMakeLists.txt
@@ -28,6 +28,7 @@ target_sources_ifdef(CONFIG_SM_CMUX app PRIVATE src/sm_cmux.c)
 target_sources_ifdef(CONFIG_SM_GNSS app PRIVATE src/sm_at_gnss.c)
 target_sources_ifdef(CONFIG_SM_NRF_CLOUD app PRIVATE src/sm_at_nrfcloud.c)
 target_sources_ifdef(CONFIG_SM_MQTTC app PRIVATE src/sm_at_mqtt.c)
+target_sources_ifdef(CONFIG_COAP app PRIVATE src/sm_at_coap.c)
 target_sources_ifdef(CONFIG_SM_MODEM_TRACE_BACKEND_CMUX app PRIVATE src/sm_trace_backend_cmux.c)
 
 add_subdirectory_ifdef(CONFIG_SM_CARRIER src/lwm2m_carrier)
diff --git a/app/overlay-coap.conf b/app/overlay-coap.conf
@@ -0,0 +1,8 @@
+#
+# Copyright (c) 2023 Nordic Semiconductor ASA
+#
+# SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
+#
+
+#Enable CoAP support over AT commands
+CONFIG_COAP=y
diff --git a/app/src/sm_at_coap.c b/app/src/sm_at_coap.c
